Heat-dissipated mechanism for outer-rotor type brushless DC fan motor

ABSTRACT

An outer-rotor type brushless fan motor is provided, wherein the outer edge of a stator of the outer-rotor type brushless fan motor is surrounded in the cup-shaped outer periphery of a rotor case of a rotor thereof, and the rotor is rotated with respect to the stator. The outer-rotor type brushless fan motor is characterized in that at least one projection and a corresponding opening thereof are formed on a surface of the rotor case, so that the projection and the corresponding opening thereof are rotated together with the rotation of the rotor, thereby heat generated by the stator is dissipated.

CLAIM OF PRIORITY

[0001] This Application is a continuation-in-part of and claims priorityunder 35 U.S.C. § 120 of U.S. application Ser. No. 10/178,969, filed onJun. 24, 2002. This application is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to an outer-rotor type brushlessfan motor, and more particularly, to an outer-rotor type brushless DCfan motor with forced-ventilation mechanism.

[0004] 2. Description of the Related Art

[0005] Please refer to FIG. 1, a partially cross sectional view of aconventional outer-rotor type brushless DC fan motor 100 is illustrated.

[0006] As shown in FIG. 1, the conventional outer-rotor type brushlessDC fan motor 100 comprises a rotor 101, a bearing assembly 201, a stator301 and a plate 401. The rotor 101 is constituted by a shaft 102, arotor case 104, a fan hub 103, and a permanent magnet 105 provided on aninner surface of a cup-shaped outer periphery of the rotor case 104. Thebearing assembly 201 comprises at least one bearing 202 and a bearinghousing 203, wherein the at least one bearing 202 is provided betweenthe shaft 102 and an inner surface of the bearing housing 203. Thestator 301 includes a plurality of silicon steel sheets 302 radiallyfixed to an outer surface of the bearing housing 203 and a set of coils303 wound around each silicon steel sheet 302, wherein the cup-shapedouter periphery of the rotor case 104 encloses an outer edge of thestator 301, and the rotor 101 is rotated with respect to the stator 301.Furthermore, the plate 401 is fixed to the bearing housing 203 so as tosupport the outer-rotor type brushless DC fan motor 100.

[0007] However, when the conventional outer-rotor type brushless DC fanmotor 100 runs, heat generated from the stator 301 enclosed in the DCfan motor 100 can not be dissipated effectively, resulting in the ratedtemperature of the running DC fan motor 100 being unable to reduce, andthen the efficiency of the DC fan motor 100 being deteriorated at hightemperature.

[0008] In view of the above, it is required an outer-rotor typebrushless fan motor capable of reducing the temperature resulted fromthe running thereof and increasing the efficiency thereof.

SUMMARY OF THE INVENTION

[0009] Thus, it is an object of the present invention to provide anouter-rotor type brushless DC fan motor capable of reducing thetemperature resulted from the running thereof and increasing theefficiency thereof.

[0010] The outer-rotor type brushless fan motor is provided according toone embodiment of the present invention, wherein a cup-shaped outerperiphery of a rotor case of a rotor of the outer-rotor type brushlessDC fan motor encloses an outer edge of a stator thereof, and the rotoris rotated with respect to the stator; the outer-rotor type brushless DCfan motor is characterized in that: at least one projection and anopening corresponding to the at least one projection are formed on asurface of the rotor case, so that the projection and the correspondingopening thereof are rotated together with the rotation of the rotor,thereby heat generated by the stator is dissipated.

[0011] It is preferred that the at least one projection connected to thesurface of the rotor case at at least one side is inwardly configured tohave a shape thereof and the opening.

[0012] A heat-dissipated mechanism for an outer-rotor type brushless DCfan motor is provided according to another embodiment of the presentinvention, wherein a cup-shaped outer periphery of a rotor case of arotor of the outer-rotor type brushless DC fan motor encloses an outeredge of a stator thereof, and the rotor is rotated with respect to thestator; the heat-dissipated mechanism is characterized in that: at leastone projection and an opening corresponding to the at least oneprojection are formed on a surface of the rotor case, so that theprojection and the corresponding opening thereof are rotated togetherwith the rotation of the rotor, thereby heat generated by the stator isdissipated.

[0013] It is preferred that the at least one projection connected to thesurface of the rotor case at at least one side thereof is inwardlyconfigured to have a shape thereof and the opening.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014]FIG. 1 illustrates a partially cross sectional view of theconventional outer-rotor type brushless DC fan motor.

[0015]FIG. 2A illustrates a partially cross sectional view of theouter-rotor type brushless DC fan motor according to an embodiment ofthe present invention.

[0016]FIG. 2B illustrates a partially cross sectional view of theouter-rotor type brushless DC fan motor according to an embodiment ofthe present invention.

[0017]FIGS. 3A to 3C illustrate side views of the modified projectionsand openings viewed along the lateral direction in FIGS. 2A and 2B.

[0018]FIG. 4A illustrates a cross sectional view of the projection andopening according to another modification of FIGS. 2A and 2B.

[0019]FIG. 4B illustrates a side view of the projection and openingviewed along the lateral direction in FIG. 4A.

[0020]FIG. 4C illustrates the projection and opening of FIG. 4 viewedfrom top of the rotor case 14.

[0021]FIG. 5A illustrates a cross sectional view of the projection andopening according to still another modification of FIGS. 2A and 2B.

[0022]FIG. 5B illustrates a side view of the projection and openingviewed along the lateral direction in FIG. 5A.

[0023]FIG. 5C illustrates the projection and opening of FIG. 5 viewedfrom top of the rotor case 14.

[0024]FIG. 6 illustrates a side view of the heat-dissipated mechanism ofthe outer-rotor type brushless DC fan motor according to anotherembodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0025] Please refer to FIG. 2A, a partially cross sectional view of anouter-rotor type brushless DC fan motor 10 according to an embodiment ofthe present invention is illustrated.

[0026] As shown in FIG. 2A, the outer-rotor type brushless DC motor 10also comprises a rotor 11, a bearing assembly 21, a stator 31 and aplate 41. The rotor 11 is constituted by a shaft 12, a rotor case 14, afan hub 13, and a permanent magnet 15 provided on an inner surface of acup-shaped outer periphery of the rotor case 14. The fan hub 13 includesa set of fan blades 13 a. The bearing assembly 21 comprises at least onebearing 22 and a bearing housing 23, wherein the at least one bearing 22is provided between the shaft 12 and an inner surface of the bearinghousing 23. The stator 31 includes a plurality of silicon steel sheets32 radially fixed to an outer surface of the bearing housing 23 and aset of coils 33 wound around each silicon steel sheet 32, wherein thecup-shaped outer periphery of the rotor case 14 encloses an outer edgeof the stator 31, and the rotor 11 is rotated with respect to the stator31. Furthermore, the plate 41 is fixed to the bearing housing 23 so asto support the outer-rotor type brushless DC motor 10.

[0027] Specifically, as shown in FIG. 2A, the outer-rotor type brushlessDC fan motor 10 is characterized in that at least one projection 16 anda corresponding opening 17 thereof are formed on a surface of the rotorcase 14, so that the projection 16 and the corresponding opening 17thereof are rotated together with the rotation of the rotor 11, therebyheat generated from the stator 31 is dissipated. The openings 17 arepositioned alternately relative to the fan blades 13 a in the radialdirection of the periphery of the rotor case.

[0028]FIG. 2B shows another embodiment of the present invention wherethe configuration is the same as that shown in FIG. 2A except that thefan hub 13 without the corresponding openings does not cover theopenings 17, which are positioned opposing to the fan blades 13 a in theradial direction of the periphery of the rotor case.

[0029] Please refer to FIGS. 3A to 3C, illustrating side views of themodified projections and openings viewed along the lateral direction inFIGS. 2A and 2B.

[0030] As shown in FIG. 3A, the projection 16 is formed such that oneend of the projection 16 is connected to the surface of the rotor case14 and the other end is inwardly folded to have a slope and the opening17 is thus formed correspondingly. Preferably, the projection 16 andopening 17 are configured by means of stamping. Therefore, theprojection 16 and opening 17 function like fan blades while both of themare rotated together with the rotation of the rotor 11, thereby an airflow caused by the forced ventilation is occurred in the outer-rotortype brushless DC fan motor 10, so that it is possible to dissipate theheat generated from the stator 31, resulting in effective reduction ofthe rated temperature of the running motor 10 effectively and theincrease of the efficiency of the motor 10.

[0031] As shown in FIG. 3B, a modification of the projection 16 andopening 17 in FIG. 3A is illustrated, wherein the slope of theprojection 16′ becomes perpendicular to the surface of the rotor case14, and an opening 17′ is thus formed on the surface of the rotor case14 correspondingly.

[0032] As shown in FIG. 3C, another modification of the projection 16and opening 17 in FIG. 3A is illustrated, wherein the end of aprojection 16″ disconnected from the surface of the rotor case 14 formsa surface that is substantially parallel to the surface of the rotorcase 14, and an opening 17″ is thus formed on the surface of the rotorcase 14 correspondingly.

[0033] Please refer to FIGS. 4A and 4B, a projection 16′″ and opening17′″ according to another modification of FIGS. 2A and 2B areillustrated. FIG. 4B illustrates a side view of the projection 16′″ andopening 17′″ viewed along the lateral direction in FIG. 4A. FIG. 4Cfurther shows the projection 16′″ and opening 17′″ from top of the rotorcase 14. As shown in FIG. 4C, the rotor case 14 at areas A and C are cutexcept for the sides of the areas A and C connected to area B (thecut-out sides of the areas A and C are shown in dashed lines) and foldedinwardly to form the projection 16′″ with trignoal prism shape and theopening 17′″ is thus formed on the areas A and C. As shown in FIGS. 4Aand 4B, the projection 16′″ connected to the surface of the rotor case14 at two sides is inwardly configured to have a trigonal prism shapethereof and the opening 17′″. Preferably, the projection 16′″ andopening 17′″ are configured by means of stamping.

[0034] Please refer to FIGS. 5A and 5B, a projection 16″″ and opening17″″ according to still another modification of FIGS. 2A and 2B areillustrated. FIG. 5B illustrates a side view of the projection 16″″ andopening 17″″ viewed along the lateral direction in FIG. 5A. FIG. 5Cfurther shows the projection 16″″ and opening 17″″ from top of the rotorcase 14. As shown in FIG. 5C, the rotor case 14 at areas A′, B′, and C′are cut except for the sides of the areas A′, B′, and C′ connected toarea D (the cut sides of the areas A′, B′, and C′ are shown in dashedlines) and folded inwardly to form the projection 16″″ with trignoalprism shape and the opening 17″″ is thus formed on the areas A′, B′, andC′. As shown in FIGS. 5A and 5B, the projection 16″″ disconnected to thesurface of the rotor case 14 merely at one side is inwardly configuredto have a trigonal pyramid shape thereof and the opening 17″″.Preferably, the projection 16″″ and opening 17″″ are configured by meansof stamping.

[0035] It is to be appreciated that one of ordinary skill in the art canchange or modify the embodiment or the modifications without departingfrom the spirit of the present invention. For example, FIG. 6illustrates the heat-dissipated mechanism of the outer-rotor typebrushless DC fan motor 10 according to another embodiment of the presentinvention, wherein a projection 16′″″ connected to the surface of therotor case 14 at one side is outwardly configured to have a shapethereof and an opening 17′″″. Further, the modifications of FIG. 6 canbe accomplished easily by persons skilled in the art by referring toFIGS. 3A to 3C, 4A and 5A.

[0036] Although the foregoing invention has been described in somedetail for purposes of clarity of understanding, it will be apparentthat certain changes and modifications may be practiced within the scopeof the appended claims. Accordingly, the present embodiments are to beconsidered as illustrative and not restrictive, and the invention is notto be limited to the details given herein, but may be modified withinthe scope and equivalents of the appended claims.

What is claimed is:
 1. An outer-rotor type brushless DC fan motor,wherein a cup-shaped outer periphery of a rotor case of a rotor of theouter-rotor type brushless DC fan motor encloses an outer edge of astator thereof, a fan hub containing a set of fan blades is provided atthe outer periphery of the rotor case, and the rotor is rotated withrespect to the stator; the outer-rotor type brushless DC fan motor ischaracterized in that: at least one projection configured in one of atrigonal prism shape and a trigonal pyramid shape, and an openingcorresponding to the at least one projection are formed on a surface ofthe rotor case, so that the projection and the corresponding openingthereof are rotated together with the rotation of the rotor, therebyheat generated by the stator is dissipated.
 2. An outer-rotor typebrushless DC fan motor, wherein a cup-shaped outer periphery of a rotorcase of a rotor of the outer-rotor type brushless DC fan motor enclosesan outer edge of a stator thereof, a fan hub containing a set of fanblades is provided at the outer periphery of the rotor case, and therotor is rotated with respect to the stator; the outer-rotor typebrushless DC fan motor is characterized in that: at least one projectionconfigured in one of a trigonal prism shape and a trigonal pyramidshape, and an opening corresponding to the at least one projection areformed on the rotor case and the hub, so that the projection and thecorresponding opening thereof are rotated together with the rotation ofthe rotor, thereby heat generated by the stator is dissipated.
 3. Themotor as recited in claim 1, wherein the openings are positionedalternately relative to the fan blades in the radial direction of theperiphery of the rotor case.
 4. The motor as recited in claim 2, whereinthe openings are positioned opposing to the fan blades in the radialdirection of the periphery of the rotor case.
 5. The motor as recited inclaim 1, wherein the at least one projection connected to the surface ofthe rotor case at at least one side is inwardly configured to have ashape thereof and the opening.
 6. The motor as recited in claim 2,wherein the at least one projection connected to the surface of therotor case at at least one side is inwardly configured to have a shapethereof and the opening.
 7. A heat-dissipated mechanism for outer-rotortype brushless DC fan motor, wherein a cup-shaped outer periphery of arotor case of a rotor of the outer-rotor type brushless fan motorencloses an outer edge of a stator thereof, a fan hub containing a setof fan blades is provided at the outer periphery of the rotor case, andthe rotor is rotated with respect to the stator; the heat-dissipatedmechanism is characterized in that: at least one projection configuredin one of a trigonal prism shape and a trigonal pyramid shape, and anopening corresponding to the at least one projection are formed on asurface of the rotor case, so that the projection and the correspondingopening thereof are rotated together with the rotation of the rotor,thereby heat generated by the stator is dissipated.
 8. A heat-dissipatedmechanism for outer-rotor type brushless DC fan motor, wherein acup-shaped outer periphery of a rotor case of a rotor of the outer-rotortype brushless fan motor encloses an outer edge of a stator thereof, afan hub containing a set of fan blades is provided at the outerperiphery of the rotor case, and the rotor is rotated with respect tothe stator; the heat-dissipated mechanism is characterized in that: atleast one projection configured in one of a trigonal prism shape and atrigonal pyramid shape, and an opening corresponding to the at least oneprojection are formed on the rotor case and the hub, so that theprojection and the corresponding opening thereof are rotated togetherwith the rotation of the rotor, thereby heat generated by the stator isdissipated.
 9. The heat-dissipated mechanism as recited in claim 7,wherein the openings are positioned alternately relative to the fanblades in the radial direction of the periphery of the rotor case. 10.The heat-dissipated mechanism as recited in claim 8, wherein theopenings are positioned opposing to the fan blades in the radialdirection of the periphery of the rotor case.
 11. The heat-dissipatedmechanism as recited in claim 7, wherein the at least one projectionconnected to the surface of the rotor case at at least one side isinwardly configured to have a shape thereof and the opening.
 12. Theheat-dissipated mechanism as recited in claim 8, wherein the at leastone projection connected to the surface of the rotor case at at leastone side is inwardly configured to have a shape thereof and the opening.